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Family and police are pleading for help finding the robber who gunned down a 39-year-old mother of five at a discount store, just two blocks away from a police station. Martha Sanchez's children say their mother worked hard and encouraged them to get a good education. Beverly White reports from South LA for the NBC4 News at 11 p.m. on Sept. 18, 2013. (Published Wednesday, Sept. 18, 2013)

The children of a 39-year-old store clerk pleaded for help Wednesday finding the robber who killed their mother while she was finishing up her shift at a South Los Angeles discount store.

"She was my role model. She was my best friend. She was everything to me and now she's gone and it's not fair this man took her away from us," said Gabriella Sanchez, 18, one of the victim's four daughters.

Daughter of Slain Clerk: "She's Gone and It's Not Fair"

The family of a 39-year-old mother of five is pleading for the public's help to find the man who gunned down Martha Sanchez as she was finishing her shift. Detectives believe the shooter went in to the Happy Bargain 99 Cents Store with the intent to rob it. John Cadiz Klemack reports from South Los Angeles for NBC4 News at 5 p.m. on Sept. 18, 2013. (Published Wednesday, Sept. 18, 2013)

"He left my little brother without a mother -- he only got her for three years."

Police are trying to track down the man who shot and killed Martha Sanchez. The beloved store clerk was gunned down while she was working at Happy Bargain 99 Cents store at 74th Street and Broadway, said Sgt. Alvarez at the Los Angeles Police Department’s 77th Street Station.

Her five children range in age from 3 to 18 years old.

A man who was trying to rob the store shot the woman at about 9 p.m. and left the scene. After the gunman ran away, a customer walked into the store to find the woman on the ground with gunshot wounds in her stomach.

The woman died at California Hospital Medical Center that night.

"It's so pointless," said detective Eric Crosson. "If the motive was robbery, take the money and go. There's no reason to hurt this lady."

Gabriella Sanchez said her mother's work ethic is her legacy. She described a woman who came home exhausted, but still wore a smile.

"She always told us, 'Don't worry, I'm here. All you guys have to worry about is school, worry about getting a better education, worry about getting a better life,'" she said.

A memorial continued to grow outside the store Wednesday evening, with mourners resting flowers against the store and one leaving behind an envelope of cash for Sanchez's five children now without a mother.

Several customers who visited the store Wednesday morning talked about what the store clerk meant to the community. The owner of the store said Sanchez worked there for one year.

"She would make my day if I go in there and talk to her," customer Lamar Wilson said. "She would ask me about my son.

"Everyday, she's in there until its closing time. So whoever it was watched her and waited until like 8 or something, when it was about to close, and they went in there and knew she would be by herself."

Investigators said they have obtained surveillance footage from inside and outside of the store.

Anyone with information in the case is urged to call 213-485-1383.

NBC4's John Cadiz Klemack and Beverly White contributed to this report.